1. Field of the Invention
The invention relates to a light source apparatus, and more particularly, to a light source apparatus having a light guide plate.
2. Description of Related Art
Along with the advancement of illumination technologies, light sources adopted by illumination devices have gradually changed from incandescent lamps and fluorescent lamps to fast-developing light emitting diodes (LEDs). LED has such advantages as low power consumption, long lifespan, environment friendliness, fast start-up, and small volume, etc. Besides, the power of LED has been increasing along with the advancement of LED techniques. Thus, LED is one of the main promising candidates to replace conventional fluorescent lamps in residential and industrial applications.
Because LED is a kind of spot light source, the light emitted by a LED is focused and therefore may cause glare to human eyes. Thus, a side incident type light source apparatus with a flat light guide plate is developed. In the side incident type light source apparatus, LEDs are disposed at a side of the flat light guide plate, and the flat light guide plate guides the light emitted by the LEDs to the front of the flat light guide plate to produce a uniform surface light source.
A lighting installation based on a light guide is illustrated in FIGS. 5-7 in U.S. Pat. No. 4,105,293. The lighting installation includes a light guide plate having a round light emitting surface and a plurality of light sources surrounding the light guide plate. In addition, a backlight module is disclosed in FIG. 1 in U.S. Pat. No. 7,063,450, wherein a special light diffusing structure is formed at the light incident side of the light guide plate such that the light incident angle is enlarged and accordingly the light uniformity is increased. Moreover, a round or oval LED backlight source is disclosed in http://tw.ttnet.net/cshow_html.jsp/%6c%65%64%b6%ea%ab%ac%be%f2%b6%ea%ab%ac%ad%49%a5%fa%aa%4f/SS/cooklang/1/prdhtm/Y/cono/40002148/item_no/14/itno/LG120/dtno/010/type1/A, wherein the light guide plate is in a round or oval shape, and the light source emits light toward the center of the light guide plate.